The invention relates to improvements in flexible continuous plastic fasteners of the rib and groove type wherein the ribs and grooves are sized and shaped to interlock when pressed together and to be releasable when pulled apart so as to form a flexible reclosable fastener.
This type of fastener is well adapted to being produced by mass production techniques wherein the fastener profiles are extruded by a continuous extrusion process wherein the heated plastic emerges from a die which has an opening sized and shaped to produce interlocking profiles that will be of a precise size and shape when cooled to interlock. These fasteners profiles can be formed as part of a fastener strip which is attached to a sheet or web, or can be formed as an integral part of a plastic film. In either arrangement the profiles function to interlock to join the sheets or permit them to be separated. A conventional use is with a reopenable bag wherein the profiles are formed along the top of the bag to interlock when being pressed together between fingers or when being pressed together by a laterally movable slider. The profiles pull apart when manually drawn apart either by grasping flanges above the profiles or by moving a slider with a separating finger in an opening direction.
In various environments it is desirable to be able to join large sheets together or join the top edges of the bag without concern as to whether the sheets have been correctly positioned. If this concern is eliminated, more speedy handling of the sheets can be effected and greater dexterity obtained for various uses. Heretofore, with fasteners which were specifically designed to interlock, if the user inadvertently laid one of the sheets in the wrong direction, that is, with the face side down, the fasteners would not interlock, and it would require inverting the sheet 180.degree.. Also, in instances where fastener strips were attached to large sheets, care had to be taken so that the strips were attached facing in the right direction unless the sheets were later to be inverted. With very large sheets, covers and tarpaulins, it was frequently difficult to reposition these sheets.
In various applications it is necessary to attach the edges or center portions of sheets to each other, and this can be accomplished by the provision of releasable and pressure closable fastener strips on the sheets. It is often desirable to be able to attach these sheets to each other either in opposing relationship, where they extend toward each other, or in adjacent relationship where they extend in the same direction.
It is accordingly an object of the present invention to provide an improved interlocking profile plastic fastener arrangement which makes it possible for the joining of sheets either in opposing relationship where the sheets extend toward each other or in adjacent relationship where they extend in the same direction, using the same attachment means.
It is an object of the present invention to provide an improved interlocking profile plastic fastener arrangement which elininates the need for orienting the direction of the fastener strip at the edge of a sheet in either direction and wherein the strip can be attached to a mating strip from either direction.
A further object of the invention is to provide an improved plastic fastener profile structure having a rib and groove attachment means wherein the profile has a unique shape with the groove being formed between two male profiles which are sized and shaped so that either of them are receivable and interlockable into a groove of the size of the groove between them.
A further object of the invention is to provide an improved fastener construction which achieves advantages heretofore not possible with prior art structures which have been available.